1. Technical Field
The present invention relates to a projector.
2. Related Art
In the past, there has been known a method of performing stacked projection of the same image on one screen (projection screen) using two projectors (see e.g., JP-A-5-107639(Document 1)). The image light thus projected by the stacked projection is roughly doubled in luminance, thus the image light projected on the screen becomes extremely bright.
However, in the case of performing the stacked projection as described above, it is not so easy to accurately overlap the image light beams from the two projectors on the screen. If the image light beams from the two projectors are not accurately overlapped, the image quality of the projection image is degraded.
As a projector in the related art capable of solving such a problem, there is proposed a projector provided with a polarization splitting optical system for splitting a light beam from a lighting device into a light beam having a first polarization component and a light beam having a second polarization component to emit the light beams respectively towards two image forming units, and a polarization combining optical system for combining the image light beams from the two image forming units (see e.g., JP-A-1-126678 (Document 2)).
According to the projector in the related art, because the light beam from the lighting device is split into the first light beam having the first polarization component and the light beam having the second polarization component to form the image light beams in the respective image forming units, and then the two image light beams are combined by the polarization combining optical system to project the combined light beam on the screen by one projection optical system, it becomes possible to accurately overlap the image light beams from the two image forming units on the screen. As a result, it becomes possible to prevent degradation of the image quality of the projection image.
However, according to research conducted by the inventors of the present invention, it proved that in the projector in the related art, even if the in-plane light intensity distribution of the light beam emitted from the lighting device was equalized using a light equalizing optical system such as a lens integrator, color shading occurred in a lateral direction (a horizontal direction) in the image light beam projected on the screen. If the color shading occurs in the lateral direction (the horizontal direction) in the image light beam projected on the screen, the image quality of the projection image is problematically degraded.